In a thermal printer, a sheet of thermally sensitive paper is moved over small selectively controlled heating elements which cause localized chemical changes in a coating on the paper. The chemically altered areas of the paper are visually discernible thus providing a presentation of the desired information. The heating elements may be configured in various arrangements. Often, the heating elements are housed in a rectangular, relatively flat integrated circuit package with the elements located adjacent one face of the package and arranged in a row. Such an integrated circuit package is described in U.S. patent application Ser. No. 508,315 entitled "A Thermal Print Head" filed June 27, 1983, by C. R. Willcox, now U.S. Pat. No. 4,516,136 issued May 7, 1985, and having a common assignee with this application.
To obtain high speed printing, a complete line of print is produced without movement of the print head i.e. by using a print head having a length equal to the width of the print area of the paper. Due to manufacturing considerations, it is not convenient to produce an integrated circuit package having a length much greater than one inch. Therefore, high speed printing is accomplished with several integrated circuit packages placed ene on end extending across the width of the paper. A particular problem in assembling such a print head is the alignment of the integrated circuit packages. The packages must be precisely positioned and securely mounted. Further, the packages must be carefully aligned to present a uniform surface to the paper and provide a single print row across the paper. To obtain acceptable print quality, the printing surfaces of the packages must exhibit less than one ten thousandths of an inch offset between adjacent packages with similar dimensional tolerances observed between contiguous heating elements of adjacent circuit packages. Additionally, the integrated circuit packages are interconnected to control circuitry, preferably, by means of a conveniently attached cable.